It is well known to use a spinstand to test various components of a hard disk assembly, such as in particular the read/write heads and the disk media. Such tests can be carried out in a manufacturing production environment, where typically every head and a proportion of disks are tested prior to being assembled into a hard disk assembly to ensure that they perform to the required standard. Testing using a spinstand can also be carried out in a research and development setting.
A spinstand typically comprises a deck, for example of granite, which is generally isolated from external sources of vibration in some way to avoid these affecting the accuracy of the test results. A spindle is attached to the deck for holding and rotating the disk. This will typically be an air bearing spindle with an integrated DC brushless motor. The spinstand has a puck for receiving the read/write head. The puck is positionable so as to move the head to a desired location under the surface of the disk. The puck will typically be positionable by a highly accurate x-y positional stage, having air bearings and linear encoders. It may also be possible to lock the puck down to the granite by application of a vacuum in order to prevent movement of the puck when in a desired position. The puck generally has some arrangement for loading/unloading the head to/from the test surface of the disk, such that the head can read and/or write a track of test data from the test surface of the disk. The puck also generally has some arrangement, such as a nanopositioner, for making very fine positional changes of the head relative to the test track.
When testing disks with a spinstand, particularly in a manufacturing environment, it is desirable to be able to swap the disk under test for a new disk as quickly and dependably as possible. It is also desirable to accelerate and decelerate the disk under test as fast as possible in order to increase throughput of disks tested. High accuracy in positioning the disk is also required. However prior art arrangements for attaching the disk to the spindle present many disadvantages in achieving these aims.
Another important consideration in attaching the disk to the spindle is accurately and dependably setting the so-called z-height of the test surface of the disk, i.e. the vertical height of the test surface relative to a datum or reference position. This is because, when loading a read/write head to a disk, the head must be vertically positioned with great accuracy relative to the test surface of the disk and so it is important that the z-height of the test surface is closely controlled when loading the disk to the apparatus. The maximum variation in the vertical positioning of the head relative to the head surface that is acceptable for the operation of the system is known as the “z-height budget”.